Rolling mill



Sept 22, 1931.

A. F. JOBKE ROLLING MILL Filed May 2, 1928 v 4 6 3 x w H 4/ [m o I m P j 1 J w L a 5 L w/ 52% 522%??? I um EEEZ E m m Figure 2.

Patented Sept. 22, 1931 PATENT OFF-ICE AUGUST F. JOBKE, or PJ ITTSBURGH, PENNSYLVANIA ROLLING MILL Application filed May 2, 1928. Serial No. 274,502.

My invention relates to rolling mills and particularly to that type which is used to produce a product of uniform thickness and relatively large width, such as plates, sheet or 5 strip, in a hot or cold state. Its object is to reduce the pressure exerted between the rolls during the rolling process and to increase the power transmitted to the rolls to a possible maximum.

In present practice the rolls for plate, sheet or strip-mills are provided with necks of a diameter smaller than that of the body, on the ends of which are cast wabblers of a still smaller diameter, the section of which generally is cruciform. This latter diameter,

as a rule, is kept to about seven-tenths to three-quarters of that of the roll body, in order to provide space for coupling boxes when the 'pass isclosed. The resistance to torque of the wabbler is therefore about onefourth or one-fifth of that of the roll body and consequently the reduction of the product is limited to the amount of power available through the wabbler. V

In rolling thin material the roll pressure is largely due to the relatively long are of contact between the rolls and the product, which fact is augmented by the fast decrease of the temperature with its reduction. Rolls of small diameter therefore decrease the pressure and allow faster rolling in the thin passes and decrease the drop in temperature in reducing the time of contact of the product with their relatively cold body.

It is the purpose of this invention to overcome the handicaps mentioned above in providing in a rolling mill rolls, which are adapted to receive and transmit an amount of 40 power fully equivalent to the torsional strength of the roll body, or in other words, to

keep the diameter of the roll body at a minimum for a given amount of power. To secure resistance against bending due to the rolling pressure, I provide a roll-hanger of a special form and other means as hacking-up members. This is accomplished as shown in the drawings, in which: t

Figure 1 is a front View of a mill showing the housings in section;

Figure 2 is a cross-section at right angles thereto;

Figure 3 shows a backing member as plied to this type of rolling mill.

In Figure 1 the upper and lower working rolls 11 are shown to be of uniform diameter throughout their length, including that portion on the wabbler end, which would ordinarily correspond to the roll-neck. The wabblers or coupling heads 12 are shown for the two rolls on opposite sides of the mill. If the wabblers are of the customary cruciform shape, their diameter is about one and onesixth times the diameter of the roll bodies to have the same torsional strength. Due to this arrangement both rolls are coupled on opposite sides of the mill through gearing or separate motors, or equivalent sources of power are provided.

Bearings 13, which advantageously may be roller bearings, adapted to carry radial as well as axial thrust, are arranged on the wabblerends of the rolls, and in case of the upper roll to carry its weight. On the opposite I ends of-the rolls there are bearings 14, mounted on journals of a diameter suflicient to carry the weight of these roll ends. These iournals may be cast on the rolls or inserted into them. The diameter of bearings 14 is smaller I than the diameter of the rolls after the latter have been turned down, so that at no time they come in contact with the other roll. All

bearings are extended horizontally, so that they may be guided in slots provided in the housings 22, as indicated in Figure 2.

In order to prevent interference in closing the pass of the mill, I arrange to guide hearing 14 of one roll with a displacement axially to the bearing 13 ofthe other roll, so that both bearings may pass each other in a vertical direction.

Since rolls of the above described character are of less resistance to bending than-the usual type, the power transmitted to them being so much larger and the roll pressure consequently high, means must be employed to prevent them from bending, such as single or double backing rolls or their equivalent. If single backing rolls are employed, i. e., all

, rolls arearranged with their axes in a vertical plane, bearings 13 and 14 on both working rolls will require guiding horizontally in the housings to prevent them from moving out of this plane; the bearings of the upper roll being also the means to suspend and lgeep the roll in contact with its backing mem- If double backing rolls or their equivalent are employed, the bearings of the upper roll are used only for suspending the roll and taking up end thrust. A horizontal displacement of the working rolls in the direction of rolling is prevented by the angular contact between working and backing rolls. In this case it is possible to dispose of hearings on the lower roll, unless they are used for fixing the same axially or counteracting any rebound, which may be caused when the piece leaves the pass.

Since backing rolls require on their necks bearings of sufiicient size to withstand relatively large pressures from the screw-down spindles, for which there is small space available, I provide for the upper working roll a roll hanger 15, which through its shape and dimensions is adapted to serve as a backing member. Instead of giving it suflicient strength only to carry the weight of the roll, I execute it in the form of a beam of a strong section adapted to transmit the full pressure, arising from the rolling process, from the screw-down spindles 16 to the upper roll by means of the rollers 17', arranged closely in two parallel rows on shafts carried on the roll hanger 15 and staggered so that spaces for bearings 18 between rollers in the two rows overlap. The balancing of the hanger and roll may be attained by the use of hydraulic plunger 19 and springs 20, as shown for the hanger and rolls in Figure 1.

The roll hanger 15 is advantageously formed as a beam of uniform resistance, having pads on its ends, adapted to be guided in the housing windows and to form seats for the screw-down spindles and breakers.

It is apparent that this arrangement is the equivalent of that with double backing rolls, having its advantages, but avoiding its drawbacks. In replacing the large bearings necessary for backing roll-necks with a large number of smaller bearings in the rollers 17 all over the length of the working rolls,- I attain a larger capacity for roll pressure and a uniform distribution of the same. The weight of the roll hanger 15 for equal strength can be made less than that even of a single backing roll, and its deflection can be made less at the same time by giving it a greater height.

In rolling strip, plate or sheet, it is essential that the final product be of uniform thickness throughout its width. The deflection of even well-backed up rolls will tend to leave the product thicker in the middle part. This tendency I overcome in the design of the backing-up member 21, Figure 3,

through arranging the 'rolls 17 in tangents to a curve which is bent in the opposite direction and of the same magnitude as the deflection curve at the prevailing roll-pressure. At this pressure the roll will therefore be perfectly straight and produce a product of uniform thickness.

For thin products, say of the order of a few thousandths of an inch in thickness, a deflection of even a mil would be quite a large deviation, and therefore a very rigid mounting of the backing rolls is essential. The bearingsor roll shaft supports 18 should be cast integrally with the beams 15 or 21, as shown, and the arrangement of the rolls on the tangent of a curve secured through carful machining or shims to correspond to one average roll pressure, which is determined by the average power input.

Having thus described my invention, what I claim is:

1. In a rolling mill a roll of uniform diameter throughout its length, having a couplin head of equal torsional strength on one en a bearing on a portion of the roll adjacent to the coupling end and a bearing of a diameter smaller than that of theroll on a journal at the opposite end.

2. In a rolling mill a pair of rolls of uniform diameter throughout their length, having coupling heads of a torsional strength equal to that of the roll bodies, located at one end of each roll and at opposite sides of the mill, a bearing on a portion of the rolls next to a coupling head and a bearing of a diameter smaller than that of the rolls on a journal at the opposite end.

3. In a rolling mill a pair of rolls of uniform diameter throughout their length, having coupling heads of a torsional strength equal to that of the roll bodies, located at one end of each roll and at opposlte sides of the mill, a bearing on a portion of the rolls next to a coupling head and a bearing of a diameter smaller than that of the rolls on a journal at the opposite end, the bearing adjacent to the coupling head of one roll being displaced axially relative to the bearing on the journal of the other roll.

4. In a rolling mill a working roll and a backing member therefor, the latter consisting of a stationary beam, bearings integral therewith to support backing rollers in contact with theworking roll, the axis of the backing rollers, when not subjected to the rolling pressure, being arranged on the tanent of a curve, which is opposite to the defiection of the beam due to the rolling pressure, so that the backing rollers are in a straight line whenjsubjected to such ressure.

In testimony of which I aflix my signature.

AUGUST F. JOBKE. 

